ECHINODEBMA — SEA-URCHINS. 
73 
<iud Hungary. In these, as in the later Echinoiclea, the 
interambulacrals were restricted to two columns,' but the 
test remained flexible. 
The British Mesozoic Echinoids include many speci- 
mens described by T. Wright in his iMonograph published 
by the Palaeontographical Society. With tlie Jurassic series 
we find the beginning of more familiar types. C'tf^an'.s 'Table-ease 
Eclwardsi from the Lias lias the jaws preserved, and the 
radioles of various sizes still on the tubercles to which 
they were attached by muscles when the animal was alive. 
Here is also Acrosahnia, with specimens of the A. lymtnlata 
Fig. 34. — Types of Fossil Echiiioidea. 1-5, Regular ; 5-8, Irregular. 
1,2, Carboniferous; 3-5, Jurassic; 5-8, Cretaceous. 1, Palaeechinus 
sphasricm, side-view. 2, Archmocidaris, interambulacral plate and its 
radiole. 3, Cidaris glatidifera, primary radiole. 4, Hemicidaris inter- 
media, side-view. 5, Salenia petalifera. 5, Dijsasier ringens. 7, Enal- 
laster Greenovi. 8, Gatopygus cohimbarhis. 5-8 are seen from above, 
with the anus towards the spectator. The figures are all somewhat 
less than natural size. (By permission of Messrs. A. & C. Black.) 
that was found in crowds near Cirencester. The Jurassic 
fossils continue with the more modified Hemicidaris and Table-case 
Pseudodiadema. Then come early forms of Diademina, such 
as Ilemipedina and Diadcmopsis, those from the Lias being 
but slightly removed from some of the Triassic species. 
They give rise, however, to more elaborate forms in the 
Oolitic rocks, e.g. the large Hcmipedina {Phymopcdina) mar- 
chamensis, with its numerous tubercles. An interesting allied 
type is Pelanechinus, in which the plates were widened and 
flexibly united. In this species have been found the little 
pincer-like appendages called pedicellariae, well known in 
living urchins, but rarely preserved on the fossils. 
